1. Field of the Invention
The present invention relates to an electrical connection box and a method for manufacturing such an electrical connection box. The invention particularly is designed to enhance a range of application and to deal flexibly with a circuit change in an electrical connection box, such as a junction box, that is to be incorporated into an automotive harness.
2. Description of the Related Art
A prior art electrical connection box, such as a junction box, has branch circuits accommodated at high density. Internal circuits are formed by a combination of wires and push-in terminals or by wires, push-in terminals and a busbar. These internal circuits may be arranged in different layers with insulating plates or the like provided between the layers of internal circuits. Internal circuits in the prior art electrical connection box are connected with external circuits by special connectors provided in the upper casing and the lower casing.
A prior art electrical connection box, as described above, is shown in FIG. 8. This prior art electrical connection box has a layered array comprising a strand of wire (single core wire) as a bottommost layer, a first insulating plate 6, a busbar 7, and a second insulating plate 8 and another strand of wire as an uppermost layer. The wire in the bottommost layer of the lower casing 1 is connected to the wire in the uppermost layer of the upper casing 2 by placing the lower casing 1 and the upper casing 2 side by side on the same plane and then laying a strand of wire w on and between the casings 1 and 2 as shown in FIG. 9. The upper casing 2 then is turned onto the lower casing 1 and fitted thereto.
The lower and upper casings 1 and 2 are formed integrally with connectors 3, relay sockets 4 and fuse sockets 5 for connection with external circuits. Push-in terminals 5 are inserted into the connectors 3. The push-in terminals 5 each have a connection portion 5a formed at one end for the connection with the wires w and for the connection with the external circuit. Push-in terminals also are inserted into the relay sockets 4 and fuse sockets 5 which are to be connected with the wire w.
The connectors 3 are formed integrally with the lower casing 1 and the upper casing 2 as described above. Thus coupling positions of wiring harnesses to be connected with the external circuits are restricted. This is a hindrance to a change in circuit design. Further, due to the restrictions, one kind of prior art electrical connection box can be used for limited types of vehicles and specifications, and may be not used for another type of vehicles and specifications.
The insertion positions of the push-in terminals 5 are restricted by the positions of the connectors 3. Hence even if the prior art electrical connection boxes are for the same type of vehicles, the wires w and the push-in terminals 5 may not be connected if the layout pattern of the wires w is changed due to a change in the internal circuits resulting from an improvement in function, because this makes it difficult to change and add circuits. To avoid these problems, the lower and upper casings need to be newly designed every time the type of vehicle is changed and/or the circuits are changed. However, this disadvantageously leads to huge production costs for the fabrication of molds.
As noted above the wire is laid in the lower and upper casings 1 and 2 that have been placed on the same plane, as shown in FIG. 9 in the manufacturing process of the electrical connection box. Consequently wire portions w-a that connect the wires in the upper and the lower layers may bulge out from the casing when the lower and upper casings 1 and 2 are assembled.
The present invention was developed in view of the above problems, and an object thereof is to prevent wires constructing internal circuits from bulging out during a manufacturing process of an electrical connection box.